Electrical furnace



G. cnzLFuacl-l4 ELECTR I CAL FURNACE Filed Sept. ll, 1937 ffy; 7.

3 Sheets-Sheet l Sept. l0, 1940. G. DELPEcH 2,214,123

ELECTRICAL FURNCE Filed Sept. 1l, 1937 3 Sheets-Sheet 2 Sept. 10, 1940.G. DELPx-:CH

' ELECTRICAL FURNACE 3 Sheets-Sheet 3 Filed Sept. 1l. 1937 o Q o a o k/l s An r A VII/a Patented Sept. 10, 1940 UNITEDv STATES "PATENT ori-lcsELECTRICAL FURNACE Application September 11, 1937, Serial No. 163,413 InFrance September 11, 1936 11 Claims.

This invention relates to furnaces, in particular those heated by heatradiation originating from electrical heating elements installed withinthe heating chamber and carried by its cover.

It is an object of this invention to permit access to the interior ofthe heating chamber during operation while its content and heaters arestill hot, without affecting substantially the tem-` perature and thecondition of that content and those heaters.

It is another object of the invention to pref vcnt entrance of air toany detrimental extent to thehcaters and other elements within theheating chamber while they are hot and the chamber is opened. Y

It is still another object of the invention to construct the cover ofthe furnace in such a way that it is capable of expanding when heated.

It is a further object of the invention to pro- 20 vide for a tightclosure of the heating chamber without preventing or rendering diiicultits being opened during operation.

It is another object of the invention to reduce the space between thecover and the heaters it Carries and the level of the melt in the shell.

These and other objects of the invention will be more clearly understoodwhen this description proceeds with reference to the drawings in whichFig. 1 shows a side elevation of a furnace ac-` cording to thisinventionfFg 2 a front eleva.-

tlon thereof, with parts broken away, Fig. 3 a cross-section along theline III- III in Fig. 2

f and, in part, side elevation thereof. Fig. 4 shows an elevation andFig. 5 a plan viewpf a table serving-to support the cover duringcharging of the shell, Fig. 6 shows partly in elevation and partly invertical cross-section a particular structure of a cover and Fig, 7 aplan View' and horizontall cross section thereof along line VII-VII inFig. 6, while Fig. 8 shows, in section, partly in elevation, anelectrical terminal of the electrodes of the furnace.

Identical reference numbers in dierent figures designate identicalparts.

In furnaces, particularly electrical furnaces for heating and smelting abatch of material, it is often desired to inspect the progress of theproccss or to add some substances to the batch or to agitate it or toperform other operations such as refining, all of which necessitatesopening of the heating chamber. In such cases air canenter the heatingchamber, affect the temperature therein and attack the batch and/orheaters and their terminals, particularly if the latter contain or areof graphite. -In order to perform such operations, suicient space mustbe left between the cover and the grill of the heaters it carries andthe level of the batch. It necessitates a large distance between thoseheaters and that level, which reduces the heating action and requires arelatively large space within the cover in which, in turn, a largevolume of air is enclosed which attacks the heaters and the batch ifcapable of oxidation at elevated temperatures. Furthermore, largeopenings made in the furnace for performing the operations mentionedabove permit the undesired admission of additional large amounts of airinto the hot heating chamber.

According to this invention it is made possible to build the furnaceflat and t0 reduce the distance of the grill of the heaters and theinner surface of the cover from the level of the batch without-impairing or preventing' the possibilityY of watching and influencingthe process, and` without exposing the heaters and terminals te theattack of fresh air if the heating chamber is opened.

According to this invention, additional means are provided which coverthe gap between the cover and the shell of the furnace .when the formeris lifted for the purposes mentioned. In addition thereto, protectivegases are admitted or a protective atmosphere is created underneath thecover and around the heaters and terminals if the latter ones areexposed to open air either when the furnace is opened for the mentionedpurposes -or when the cover is removed for charging the shell. Theprotective gases or atmosphere are shut oi, however, when the furnace isclosed. Thus, the space and the volume of gas above the level of thebatch in the closed chamber are reduced to a desirable minimum whilesuicient space is left for alecting the 40 batch during operation bylifting the cover without permitting, however, undesired or detrimentalaccess of fresh air into that chamber. By removing the cover from theshell the latter can be conveniently charged. The heaters and terminalsare protected against air while they are hot, and their life iscorrespondingly prolonged. Referring to the drawings', Figs. 1, 2 and 3,the furnace comprises a base such as a shell or receptacle B for thebatch or material to be melted or heated and a curved cover V. Theshellconsists preferably substantially of hearth I, a bottom ofrefractory material which is outwardly surrounded by a lining 3 ofrefractory material possessing low heat conductivity and an outsidemetal mantle 2. The upper troughshaped surface of the hearth is shapedso as to receive the material to be heated. The upper edge of the mantleis provided with a circumfer- 5 ential groove 4, which contains sand orany other suitable powdery or plastic material, to receive a downwardlyprotruding rim 5 of the cover. Thereby gas-tight closure is securedduring the melting process.

A spout or nozzle 8 is arranged in the axis of the furnace and isprovided with an inclined I channel 1 the inner end of which lies abovethe level of the melt. This channel is closed by means of a plug duringthe melting or heatingprocess. In the cover V electrical terminals 8 and9 for electrodes I0 are arranged. In the exemplication of the drawing,three such electrodes with pairs 8, 9 of terminals are shown. Theelectrodes can be electrically arranged in series or in parallel if theyare supplied with director singlephase current, or in star or intriangle connection if they 4are supplied with three-phase current.

A circumferential tubular rim I I 'which is arranged at the lower edgeof the cover V is provided with a number of holes I2 (Figs. 2, 3) on itsinside facing the interiorof the shell. These holes are preferablyarranged along the longer sides of the rim. Tubes I3 (Figs. land 2) areconnected with the longer sides of tubular rim II and with a flexibleconduit I3a through tube I4 and casing I5 in which a valve (not shown)is arranged: This valve is normally open but autonatically closed if thecover V contacts the shell B and a stem I6 connected with the valve isplaced on an abutment I 6a provided-on the outside vof the mantle `2.

As it is to be seen in Figs. 2 and 3, the rim II provided with a conduitfor a iiuidis received by and submerged in the groove 4. The heatingchamber of the furnace if closed is surrounded by the refractorymaterial of the shell and the cover, and the rim II is protected againstthe heat developed in that chamber by the upper edge of the lining 3provided with two rails 2| supported byrollers 22 rotatably arranged ona frame 23 which is pivotally supported at 25 by brackets 26 mounted ona base 21. l,

In operation, the cover V is lowered upon the shellB, and the heatingchamber is thereby tightly closed. 'I'he material deposited upon thesurface I is heated by -radiant heat developed by the heaters I0. Ifdesired the furnace can be oscillated around its longer axis due to itssupport by rails 2l and rollers 22. Stops, not shown, can be employed inorder to limit that oscillating movement and to ensure that the batchdoes not overow the upper edges of the shell. If it is desired, e. g.,to observe the state of the material within the furnace while theheating process proceeds, or if it is desired to add material to thebatch in the furnace, one'can lift and n turn the cover V which at itsrear end is plvotally A shim l1 of sufneienuy heat resisting mataconnected with the shell by means of a pivot 24 received by a bearing24a secured to the shell. This bearing is open on its upper side so thatthe cover with its pivot 213 can be raised and removed, as it will lateron be described herein in more 5 detail. If the cover is raised andturned on its pivot 24, it ultimately arrives at the position V1, shownin dash-dotted lines in Figs. 1 and 2. 'I'he shield I'I being connectedwith the cover by means of the screws 2U was taken along by the cover l0and thereby turned around its pivots I8 into the position also shown indash-dotted lines in Figs. l and 2. Thereby the gap resulting betweenthe shelland the cover when the latter was raised is covered by theshield Il, and the entrance of 15 surrounding fresh air into the hotheating chamber is substantially prevented except for the small area ofthe aperture I'Ia in the shield which, when the shield was raised,arrived at the position 28 shown in dash-dotted lines in Fig. 2.lThrough 20 that aperture the interior of the heating chamber can beconveniently watched during operaltion and any desired manipulation caneasily be performed.

I Thevalve in the casing I5 was closed while the 25 cover rested uponthe shell. If the cover is raised, the valve stem I6 is lifted from theabutment I6a and opens so that any desired iiuid substance suppliedthrough the conduit I 3a can flow into the hollow interior of the rim II. When this rim 30 is lifted with the cover it leaves the groove d andits holes I2 face now the interior of the heating chamber so that thefluid substance discharges freely through those holes into that chamberunder the cover V above the level of the batch 35 or melt/in the shell,surrounding or covering from below the heaters and the terminals. Thesubstance may be a liquid which evaporates when it contacts the hotheaters and terminals thereby forming around them a protectiveatmosphere. 4,0 Or the substance can be, e. g., a neutral gas which isprotective by its nature, or it can be a combustible gas which uponcontact with the hot heaters or terminals will iname, and itscombustiony products will form the desired protective 45 atmosphere. Inany case. due to this protective atmosphere, air entering the heatingchamberv through the aperture 28 cannot reach and attack the material ofthe heaters or terminals made .of graphite.

is` preferably entirely removed by suitable means.

such as a hoist; this is possible due to the fact that thel bearing 24ais open on its upper side. The cover can then temporarily be depositedupon a support shown in Figs. 4 and 5, and the re- 65 ceptacle B isfreely accessible and can be conveniently charged. By raising the coverthe valve within the casing I5 is automatically opened in the waydescribed above, and a protective atmosphere is created around the`heaters and their 70 terminals. This as also advisable in case theelectrical current feeding the heaters has been cut o after the heatingwas completed while the heaters .remained still hot.

The support upon which the cover is posi-*7s tioned consistssubstantially of a flat receptacle 30 forming a table on a level withthe upper opening of the shell and filled with refractory powderymaterial which is supported by feet 3|.-

A groove 32 filled with refractory material such as sand forms the rimofthat table and resembles the rim 4 of the shell. The rim II of thecover enters into the groove 32, and the stemIG contacts the edge ofthat groove whereby the valve in casing I5 is automatically closed andthe supply of protective substance into the hollow rim I I is shut off.This is permissible because no `air can accede to the heaters and theirterminals which are secluded from the air by table 30.

The cover may be of any known or desired structure. In order to obtain aflat and resilient structure as it is shown in Figs. 6 and 7, it is madeof a frame 33 consisting of four U-shaped iron parts bent at an angle of15 at their ends through which bolts 34 traverse and press them togetherby means of springs 35. To this frame a covering of metal 31 is solderedat 36a which along its diagonal is provided with folds or gussets 38which reach the lowerlevel or surface of the frame 33 andserve to permitexpansion of the parts of the frame when heated. Bricks 32a ofrefractory material are mounted on the frame 33 and form a base for alling of suitable material introduced through an opening of the covering31 between the latter one and those bricks. The opening in the coveringis `closed by a detachable member 39. Cups 40 are tilted over the headsof the bolts 34 and held in contact- On two side parts 42-of the frame33 passages for the terminals areprovided which consist of members 43 ofgraphite to receive the electrodes proper, as shown in Fig. 3. 0n themember 43,v

Fig. 8, a tubular part 45 is screwed or otherwise fastened by means ofbolts (not shown) and an insulating intermediary piece 44. Inside thattube 45 another' member 46 is slidably arranged. A bellows-foldedcylindrical cuff 48 surrounds member 46 and is soldered to it at one endand to the tube 45 at its other end. The support 43 of graphite ispressedinto that member 46. A cooling channel 50 is provided in member46 and isl connected through tube 49 with a supply of cooling water. Aclamp 5I which is to receive the end of the electrical cable is providedwith a cone 52 which enters into the member 46. A spring 52d coiledaround an insulating piece 53 presses the cone 52 permanently intomember 46 and thereby maintains the desired electrical contact.

fro

is open. The gas-tightly closing means can be made as compact andeincient as possible as is known in the art, and properly protectedagainst the heat developed in the furnace during operation. Theadditional means arranged outside the cover and base independent fromthe means for gas-tightly closing the furnace, may consist of a simpleshield which does not interfere in any way With operating the furnaceand particularly opening it. The cover may be lifted vertically ortilted on a pivot relative to the base, and any desired distance betweenthe cover and base of the opened furnace can be taken care of by properdimensioning of the shield. Any desired position of the opening in theshield relative to the gap can be adjusted according toany requirementof operation.

It is to be understood that the invention is not, limited to anyparticular feature hereinbefore described by way of example only but tobe derived in its broadest scope from the appended claims.

What I claim is:

1. A furnace comprising, in combination, parts forming a base and acover, said parts capable of having different relative positions andarranged to enclose a heating chamber in one and to be at leastpartially spaced from and to leave a gap between each other in anotherof said relative positions, said parts provided with rigidly attachedmeans cooperating in said first position to gastightly seal said chamberand to permit access to it substantially all over said gap Vin saidother position, separate screening means having an opening arrangedkoutside said parts and their sealing4 means, said screening meansmovable relative'to said parts and their sealing means into differentpositions in one of which said gap is substantially covered and accessto it permitted through said opening, and means operatively connectingsaid screening means with one of said parts for placing said screeningmeans into said covering position when said parts are in ,said spacedposition.

2. A smelting furnace comprising, in combination, parts forming a baseand a cover, said parts capable of having diierent relative positionsand arranged to enclose a smelting chamber in one and to be at leastpartially spaced from and leaving a gap between each other in .anotherof their relative positions, means for gas-tightly connecting said partsin said first mentioned position, additional means movable independentlyfrom said first mentioned means arranged outside said parts and adaptedto substantially cover said gap, said means provided with an ,openingpermitting in their covering position access to a part of said gap,andadjustable means operatively connecting said additional means withone of said parts for securing said additional means and its opening inproper and adjustable position relative to said gap when said parts arespaced from each other.

3. A smelting furnace comprising, in combination, parts forming areceptacle for a batch and a cover, said parts pivotally connected witheach other so as to be capable of occupying different relative positionsin one of which they enclose a smelting chamber while in another onethey leave a gap between each other, means for gastightly connectingsaid parts yin said first mentioned position, additional means movableindependently from said rst mentioned means arranged outside said partsadapted to cover said gap and provided with an opening pernitting accessto said gap in their covering position, said additional means pivotallyconnected with one and adjustably with the other of said part so as -topermit adjustment of the position of said additional means and theiropening relative to s'aid gap.

4. An electrical furnace comprising, in combination, parts forming abaseand a cover having a downwardly projecting rim, said parts capable ofhaving different relative positions and arranged to enclose in one ofthem a heating chamber and in another of them to be at least partiallyspaced and to leave a gap between each other; means associated with saidparts for gastightly connecting said parts in said rst mentionedposition; additional means arranged independent from said firstmentioned means outside said parts and operatively connected with one ofsaid parts so as to substantially cover said gap and provided with anopening permitting access to a part of said gap in their coveringposition; electrical heater elements sensitive to open air at elevatedtemperature arranged inside and supported by said cover; controlledmeans combined with and extending over a substantial partl of the insidecircumference of said rim for causing a protective atmosphere aroundsaid heater elements; and means dependent upon the relative position ofsaid parts for controlling said controlled means, rendering saidcontrolled means operative when said parts are spaced from each otherand inoperative when said parts are in their closed position.

5-. A iurnacecomprising, in combination, partsy forming a receptacle formaterial to be heated and a cover, said parts pivotally and detachablyconnected with each other so as to be capable o'f occupying differentrelative positions in one of which they contact each other and enclose aheating chamber, in another one they are inclined Vtowards and leave adesired gap between each other, While lwhen detached they are entirelyseparated from each other, and means pivotally connected with one endand adjustably and detachably connected with the other of said parts,said means adapted to substantially cover said gap and capable ofpermitting access to a part of said gap if connected with said otherpart in its said other relative position.

6. An electrical furnace comprising, in combination, parts forming abase and a Acover having a downwardly projecting rim; said parts capableof having diierent relative positions and arranged to enclose in one ofthem a heating chamber and in another of them to be at least partiallyspaced from and to leave a gap between each other; means for gas-tightlyconnecting said parts in said first mentioned position; additional meansarranged independent from said first mentioned means outside said partsand operatively connected With oneof said parts so as to substantiallycover said gap and permitting access to part o1' said gap; electricalheater elements sensitive to open air at elevated temperature arrangedinside and supported by said cover; controlled means combined with andextending over a substantial part of the inside circumference of saidrim for admitting a gas under said cover for causing a. protectiveatmosphere around said heater elements; and means dependent on therelative.position of said parts for-controlling said controlled means soas to admit gas when said parts are spaced from each other and to Ihutoi that gas when said parts are in their closed position.

'7. An electrical furnace comprising, in comcal heater elementssensitive to open air` at ele-f vated temperature arranged inside andsupported by said cover; controlled means for admitting a gas under saidcover for causing a protective atmosphere around said heater elements,said means associated with one of said parts and arranged to lie insidesaid additional means in said spaced position and outside said heatingchamber in said' closed position of said parts; and automatic meansdependent on the relative position of said parts for controlling saidgas admitting means so as to admit gas under-said cover when said partsare in a spaced position and to shut o'i vthat gas when said parts arein their closed position.

8. An electrical furnace comprising, in combination, parts forming abase and a cover, said cover provided with a downwardly projecting rim,said parts capable of having different relative positions and arrangedto enclose in one of them a heating chamber and in another to vbe atleast partially spaced from and toleave a gap between eachother; meansgas-tightly connecting said parts in said rst mentioned position;additio-nal means arranged independent from said rst mentioned meansoutside lsaid parts and operatively connected with one of said parts soas to substantially cover said gap and permitting access to part of saidgap; electrical heater elements sensitive to open air at elevatedtemperature arranged inside and supported by said cover; a conduitformed in said rim and provided with discharge openings directedsubstantially towards said heaters for admitting a protective gas belowsaid cover around said heaterelements; and means dependent on therelative position of said parts for controlling the admission of gas tosaid conduit, so as to admit gas when said parts are spaced from eachother and to shut it oi when said parts are in their closed position.

v9. In an' electrical furnace as described in, claim 8, said baseprovided with an upwardly projecting rim of refractory material, saidlatter rim, when'said chamber is closed, positioned inside and close tosaid rim of the cover.

10. An electrical furnace comprising, in combination, parts forming areceptacle for material to be heated and a cover', said parts capable ofhaving diierent relative positions and arranged to enclose in one ofthem a heating chamber and in another one of them to be at leastpartially spaced from and to leave a gap between each other; means forgas-.tightly connecting Asaid parts in said first mentioned position;means arranged independently from said first mentioned means outside ofsaid parts adapted to substantially cover said gap and capable ofpermitting access to part of said gap; electrical heaters sensitive toopen air at elevated temperatures, said heaters supported by said cover;means for admittinga gas under said cover for causing a protectiveatmosphere around said heaters, if

said parts are spaced from each other, said gas admitting meansconnected with one of said parts and arranged to lie inside said meanscovering said gap in said spaced position and outside said heatingchamber in said enclosing position of said parts. Y

11. An electrical furnace comprising, in cornbination, parts forming areceptacle for material to be heated and a cover, said parts capable' ofhaving different relative positions and arranged to enclose in one ofthem a heating chamber and in another of them to be atleast partiallyspaced from and to leave a gap between each other; means arrangedindependently from said rst mentioned means outside of said partsadapted to substantially cover said gap and capable of permitting accessto part of said gap; electrical heaters sensitive to open air atelevated temperatures, said heaters supported by said cover; means forgas-tightly connecting said parts in said first mentioned position andincluding means for admitting a gas under said cover for causing aprotective atmosphere around said heaters if said parts are spaced fromeach other, said gas admitting means arranged to lie inside said meanscovering said gap in said spaced position and to gas-tightly engage saidother part outside said heating chamber in said enclosing position ofsaid parts.

GASTON DELPECH.

